Question

how it would be possible to have a change in a single base of DNA, but have the protein NOT change and be functional

Answer 1

It Wouldn’t necessarily be possible

Answer 2

It would be possible because This happens because substitution of base or new base codes for the same amino acid. example in codon AAA if 3rd A gets change to G due to mutation and become AUG. ... Thus when amino acid is not changed the polypeptide will not change hence no confirmational or functional change in the protein